The effects of beta-adrenergic blocking agents in patients with TGA and congestive heart failure due to systemic ventricular dysfunction have never been studied. To our knowledge, only one case report suggests that carvedilol may potentially improve systemic ventricular functions and volumes in these patients. This study will identify the potential merits of beta-blocker therapy in patients with TGA and CHF and could theoretically lead to a multi-institutional prospective analysis of beta-blocker therapy in adult patients with congenial heart disease and CHF.